Preparation And Electrocatalytic Performance Of Metal Sulfide Nanomaterials For Electrochemical Synthesis Of Ammonia

Ammonia（NH₃）,the most widely produced chemical,plays an indispensable role in modern production and life.Typically,it is artificially synthesized from nitrogen and hydrogen through the Haber-Bosch method found in1913.The Haber-Bosch process consumes～5%of global energy and releases～1.5%of the global greenhouse gases,due to the method process at high temperature and high pressure.Making use of water as the proton source and electric energy to drive the ammonia synthesis reaction will reduce the fossil fuel consumption and CO₂ emission and is thus regarded as a green and sustainable alternative to the conventional Haber-Bosch process.Among them,the electrochemical synthesis of ammonia is an economical and environmentally friendly process carried out at ambient condition.And it is of great significance to the sustainable development of mankind.However,the main reason to limit large-scale commercial electrochemical ammonia is the low performance of the catalyst.Therefore,it is important to develop a catalyst with high activity,selectivity and with good stability.In this research,Sb₂S₃ nanomaterials were synthesized by solvothermal method.The performance of electrocatalytic ammonia synthesis was studied.First,we explored the influence of reaction conditions such as reaction temperature and reaction time on Sb₂S₃.The experimental results showed that the morphology of Sb₂S₃-Tu was mainly granular,as well as the size of the Sb₂S₃-Tu increased with the increase of the reaction time.In addition,we prepared Sb₂S₃-L with L-cysteine.When the mass of L-cysteine doubled,the morphology of Sb₂S₃-L changed from granular to tubular structure,and the size of Sb₂S₃-L became significantly smaller.Among them,Sb₂S₃-L2 showed the highest catalytic performance,while the ammonia yield was 13.14 g h^-1 mg^-1_cat,and the FE was 15.83%.Particularly,Sb₂S₃ showed good stability during the cycle test.There was no production of N₂H₄ in the electrolyte after the electrocatalytic reaction,indicating that Sb₂S₃ exhibited higher selectivity in the electrocatalytic synthesis of NH₃.In this study,CTS nanomaterials were successfully synthesized by solvothermal method,and the electrochemical nitrogen reduction performance was explored.We first explored the influence of reaction temperature,reaction time,and the ratio of reactants on the microscopic morphology of CTS nanomaterials.Compared with the CTS-Tu synthesized by Tu with a larger particle size,the CTS-L synthesized by L-cysteine was more uniform and smaller.In addition,the results of E-NRR tests showed that the ammonia yield and FE reached the maximum when the potential was-0.5 V（vs.RHE）.Among them,CTS-L2 showed the highest catalytic performance,while the ammonia yield and the FE were 10.86 g h^-1 mg^-1_cat and 7.61%respectively.Particularly,the CTS showed good stability during the cycle test.There was no production of N₂H₄ in the electrolyte after the electrocatalytic reaction,indicating that CTS exhibits higher selectivity in the electrocatalytic synthesis of NH₃.